DEM

http://www.satimagingcorp.com/svc/dem.html

Digital Elevation model displays an image of regularly spaced grid of elevation points. It uses a three dimensional geodetic system with the x-axis as easting’s, y axis as northing’s and z axis is the elevation.  This is an example of a DEM and displays an image of Eritrea Africa. This is an IKONOS image, which means the data, is from IKONOS satellite sensors.